Dispensers are used in commerce and science for delivering fluids and beneficial agents to many varied and diverse environments of use. For example, patentee Theeuwes in U.S. Pat. No. 3,760,984 discloses a dispenser useful for these purposes. The dispenser comprises a chamber formed of a shrinkable polymer carrying on its outer surface a layer of an osmotic solute and a distant layer of a semipermeable polymer. The dispenser has a means for filling the chamber. The dispenser delivers its contents by imbibing fluid into the dispenser, wherein the fluid dissolves the solute and forms a solution, which solution exerts pressure against the chamber, causing it to shrink and deliver its contents from the dispenser. Another dispenser is disclosed in U.S. Pat. No. 3,865,108 by patentee Hartop. The Hartop patent describes a dispenser that comprises components arranged concentrically and consisting of an inner collapsible tube, a water swellable base member that surrounds all but one end of the tube, and an optional water permeable skin around the base member. The dispenser operates by the member absorbing water and expanding, which expansion squeezes the collapsible tube causing its contents to be expelled from the free end of the tube. In U.S. Pat. No. 3,987,760, Eckenhoff et al., discloses an improved osmotic dispenser for delivering agents. The dispenser consists of a layer of an osmotically effective solute positioned between a bag and a semipermeable wall. The improvement relates to a conduit for filling the bag. The dispenser operates by solute imbibing fluid into the dispenser, which fluid generates hydraulic pressure that is applied against the bag, causing it to squeeze inwardly forcing agent from the dispenser. In U.S. Pat. No. 3,971,376, Wichterle discloses a dispenser for delivering an agent, which dispenser consists of a capsule having unitary walls formed of a gel material swellable in fluids. A textile fabric is imbedded in the material for imparting strength and minimizing problems due to poor mechanical properties associated with the material that occurs during fluid uptake used to power the dispenser. Another dispenser is disclosed in U.S. Pat. No. 3,995,631 by Higuchi et al. The dispenser in this patent comprises a bag bearing on its outer surface a layer of an osmotic solute, and an outer wall formed of a material having in at least a part controlled permeability to fluid. In operation, the dispenser imbibes fluid and forms a solution of the solute, which solution squeezes the bag and thusly delivers agent from the dispenser. In copending U.S. patent application Ser. No. 06/115,750 and now U.S. Pat. No. 4,304,232 issued on Dec. 8, 1981, applicant Michaels discloses a dispenser comprising a wall that governs the passage of fluid into the dispenser, a container that can change in volume and has a passageway dimensioned for controlling the rate of release from the container, and a lamina formed of a material that absorbs fluid and is positioned between the wall and the container. The dispenser delivers agent by the combined operations of the wall, the lamina, the container, and the passageway acting together for urging the agent from the dispenser.
While the above dispensers are useful for delivering numerous agents to many environments of use, and while the dispensers represent a major advancement in the dispensing art, it will be appreciated by those versed in the art, there are instances where a dispenser made with an inventively novel improvement would also enjoy a wise use and application in the dispensing art. For example, if a dispenser is made from a wall forming material that combines both semipermeable and hydrophilic properties into a single material suitable for powering the dispenser, thereby providing an improvement in the dispenser, by advancing the structural property and enhancing the operability of the dispenser, while simultaneously reducing the number of steps needed to make the dispenser, such a dispenser would have immediate acceptance, and it also would represent a valuable contribution in the fields of science and commerce.